While old automotive brake devices are mostly hydraulic ones, with an introduction of sophisticated brake control systems such as anti-lock brake control systems (ABS's), electric brake devices, which permit such sophisticated brake control without the need for complicated hydraulic circuits, are gathering attention these days. Such an electric brake device includes an electric linear motion actuator including a linear motion mechanism for converting the rotary motion of an electric motor to a linear motion of a brake pad, whereby when the electric motor is actuated by e.g. a signal indicative of the depression of the brake pedal, the brake pad is moved linearly and pressed against a brake disk, thereby applying a braking force to the wheel (see, for example, the below-identified Patent documents 1 and 2).    Patent document 1: JP Patent Publication 6-327190A    Patent document 2: JP Patent Publication 2006-194356A
In such an electric brake device, since the output of the electric motor is a product of the torque and the number of revolutions of the motor, the output of the electric motor is zero while the braking force is maintained. However, while the braking force is changing, the electric motor generates an output in proportion to the number of revolutions of the motor, so that the motor consumes electric power.
Thus, any fluctuations in braking force due to external factors such as electric signal noises, quantizing noises, or uneven wear of the brake pads could cause the electric motor to oscillate at high speed, and increase its operating frequency, thereby markedly increasing the power consumption.
Accordingly, an object of the present invention is to reduce the power consumption of such an electric brake device, while reducing fluctuations in braking force of the brake device to within a permissible range.